Conventional strips suitable for the above-described use comprise two structural shapes of polymeric material connected together by a continuous rib which has constant dimensions and which is also formed of polymeric material with the function of the rib being to connect together the two structural shapes.
Of these two structural shapes, the former has the function of anchoring the strip to the motor vehicle body and comprises means for securing the strip to the vehicle body, while the latter has the function of providing a sealing of the strip and is compressed against the contour of the side doors, trunk doors and the like when these latter are closed relative to the opening of the motor vehicle body.
Usually, the second structural shape is in the form of a tubular body formed of foamed material and is elastically deformable. Herein, the term "tubular body" means a body provided with a cavity in a radially innermost position with respect to the body, the section of which can have any configuration whatsoever; therefore, the contours of the inner cavity and of the outer surface of the tubular body can be, for example, circular, non-concentric, elliptical, polygonal with rectilinear or curvilinear sides equal or different from one another, and combinations of the above geometrical configurations.
The problem that appears in the strips in question is to guarantee a reliable and efficient sealing at any point between the side door, trunk door and the like and the contour of the motor vehicle body to insulate the interior compartment of this latter against water infiltration and noise caused by outside sources and to require at the same time the least possible effort by the user to bring the side doors, trunk doors and the like into closing position.
The solution of the above problem requires the mediation of the above-noted two opposite requirements.
In fact, to ensure a good sealing it is necessary that the strip exert a fairly high and uniform specific pressure on the contour of the door of a motor vehicle, and this in turn requires a fairly high force applied on the strip by the door in the closing position. This is clearly in contrast with the requirement of the user to exert the least possible effort and, consequently, to apply the least possible force to close the door itself.
The solution of the problem in question is complicated by the fact that in a motor vehicle having a door in its closing position, the distance between the contour of the opening and the contour of the door closing the opening is not constant, but is variable also in a relatively considerable measure not only between the various openings of the body of the same motor vehicle, but also in the openings of motor vehicles of different models.
In order to solve the above-described problem, the heretofore known strips vary the dimensions of the second tubular structural shape of foamed material.
More precisely, in the known strips the second tubular structural shape of foamed material is variable longitudinally along the strip in its outer diametral dimensions, thickness and thickness profile.
The drawbacks of the above-described known strips derive from the fact that the second structural shape of foamed material has dimensions variable along the strip as set forth above.
In fact, it is very difficult and requires the use of very complicated and consequently very delicate production equipment to realize with precision, on industrial scales, variations of the outer diameter, thickness and distribution of thicknesses along the tubular structural shape, which is of foamed material.
It is noted that the variations in question must be carried out in fairly reduced portions and quite near one another, since the total length of a strip usually does not exceed three meters and also that the variations that permit the solution of the problem are effected contemporaneously with the foaming of the material. As a result, formation of these variations yields the risk of altering the foaming process simply as a consequence of said variations of dimensions.
The consequence of the foregoing results in practice in an insufficient utility by known strips to solve reliably on an industrial scale the previously stated problem connected with the sealing strips of motor vehicles.